U.S. patent application number 15/801570 was filed with the patent office on 2018-09-13 for shift register with fault tolerance mechanism and driving method thereof, and gate driving circuit.
The applicant listed for this patent is BOE Technology Group Co., Ltd., Hefei BOE Optoelectronics Technology Co., Ltd.. Invention is credited to Junsheng Chen, Xianjie Shao.
Application Number | 20180261178 15/801570 |
Document ID | / |
Family ID | 59138551 |
Filed Date | 2018-09-13 |
United States Patent
Application |
20180261178 |
Kind Code |
A1 |
Shao; Xianjie ; et
al. |
September 13, 2018 |
Shift Register with Fault Tolerance Mechanism and Driving Method
Thereof, and Gate Driving Circuit
Abstract
Provided are a shift register and a gate driving circuit. The
shift register includes: a pull-up driving circuit connected to an
input signal terminal, a first voltage terminal and a pull-up node;
a pull-up circuit connected to a clock signal terminal, the pull-up
node and an output terminal; a pull-down driving circuit connected
to a second voltage terminal, a third voltage terminal, the pull-up
node and a pull-down node; a pull-down circuit connected to the
second voltage terminal, the pull-down node, the pull-up node and
the output terminal; and an interference removing circuit connected
to an interference removing signal terminal and the pull-down node,
and configured to transmit an active interference removing signal
to the pull-down node to charge the pull-down node when an
interference removing signal outputted at the interference removing
signal terminal is at an active control level.
Inventors: |
Shao; Xianjie; (Beijing,
CN) ; Chen; Junsheng; (Beijing, CN) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
BOE Technology Group Co., Ltd.
Hefei BOE Optoelectronics Technology Co., Ltd. |
Beijing
Hefei |
|
CN
CN |
|
|
Family ID: |
59138551 |
Appl. No.: |
15/801570 |
Filed: |
November 2, 2017 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
G09G 2310/0286 20130101;
G09G 3/3677 20130101; H03K 17/6871 20130101 |
International
Class: |
G09G 3/36 20060101
G09G003/36; H03K 17/687 20060101 H03K017/687 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 7, 2017 |
CN |
201710132394.X |
Claims
1. A shift register, comprising: a pull-up driving circuit
connected to an input signal terminal, a first voltage terminal and
a pull-up node, and configured to output a voltage signal of the
first voltage terminal to the pull-up node when an input signal of
the input signal terminal is at an active input level; a pull-up
circuit connected to a clock signal terminal, the pull-up node and
an output terminal, and configured to output a clock signal of the
clock signal terminal to the output terminal when a pull-up signal
of the pull-up node is at an active pull-up level; a pull-down
driving circuit connected to a second voltage terminal, a third
voltage terminal, the pull-up node and a pull-down node, and
configured to control a potential at the pull-down node; a
pull-down circuit connected to the second voltage terminal, the
pull-down node, the pull-up node and the output terminal, and
configured to pull down the output terminal and the pull-up node to
a voltage signal of the second voltage terminal when a pull-down
signal of the pull-down node is at an active pull-down level; and
an interference removing circuit connected to an interference
removing signal terminal and the pull-down node, and configured to
transmit an active interference removing signal to the pull-down
node to charge the pull-down node when an interference removing
signal outputted at the interference removing signal terminal is at
an active control level.
2. The shift register of claim 1, wherein the interference removing
circuit comprises an interference removing transistor, a gate and a
first electrode of the interference removing transistor are both
connected to the interference removing signal terminal, and a
second electrode of the interference removing transistor is
connected to the pull-down node.
3. The shift register of claim 1, wherein the interference removing
signal is an active control level signal after abnormity occurs to
an output signal of the shift register and before a next frame
signal arrives.
4. The shift register of claim 1, wherein the pull-up driving
circuit comprises a pull-up driving transistor, a gate of the
pull-up driving transistor is connected to the input signal
terminal, a first electrode of the pull-up driving transistor is
connected to the first voltage terminal, and a second electrode of
the pull-up driving transistor is connected to the pull-up
node.
5. The shift register of claim 1, wherein the pull-up circuit
comprises an output transistor, a gate of the output transistor is
connected to the pull-up node, a first electrode of the output
transistor is connected to the clock signal terminal, and a second
electrode of the output transistor is connected to the output
terminal.
6. The shift register of claim 1, wherein the pull-down driving
circuit comprises: a first pull-down driving transistor, a gate of
the first pull-down driving transistor being connected to a second
electrode of a third pull-down driving transistor, a first
electrode of the first pull-down driving transistor being connected
to the third voltage terminal, and a second electrode of the first
pull-down driving transistor being connected to the pull-down node;
a second pull-down driving transistor, a gate of the second
pull-down driving transistor being connected to the pull-up node, a
first electrode of the second pull-down driving transistor being
connected to the pull-down node, and a second electrode of the
second pull-down driving transistor being connected to the second
voltage terminal; the third pull-down driving transistor, a gate
and a first electrode of the third pull-down driving transistor
being connected to the third voltage terminal; and a fourth
pull-down driving transistor, a gate of the fourth pull-down
driving transistor being connected to the pull-up node, a first
electrode of the fourth pull-down driving transistor being
connected to the second electrode of the third pull-down driving
transistor, and a second electrode of the fourth pull-down driving
transistor being connected to the second voltage terminal.
7. The shift register of claim 1, wherein the pull-down circuit
comprises: a node pull-down transistor, a gate of the node
pull-down transistor being connected to the pull-down node, a first
electrode of the node pull-down transistor being connected to the
pull-up node, and a second electrode of the node pull-down
transistor being connected to the second voltage terminal; and an
output pull-down transistor, a gate of the output pull-down
transistor being connected to the pull-down node, a first electrode
of the output pull-down transistor being connected to the output
terminal, and a second electrode of the output pull-down transistor
being connected to the second voltage terminal.
8. The shift register of claim 1, further comprising: a storage
circuit, a first terminal of the storage circuit being connected to
the pull-up node and a second terminal of the storage circuit being
connected to the output terminal, and the storage circuit being
configured to be charged when the voltage signal of the first
voltage terminal is passed to the pull-up node.
9. The shift register of claim 1, further comprising: a reset
circuit connected to a reset signal terminal, the second voltage
terminal and the pull-up node, and configured to pull down the
pull-up node to the voltage signal of the second voltage terminal
when a reset signal at the reset signal terminal is at an active
control level.
10. The shift register of claim 9, wherein the reset circuit
comprises: a reset transistor, a gate of the reset transistor being
connected to the reset signal terminal, a first electrode of the
reset transistor being connected to the pull-up node, and a second
electrode of the reset transistor being connected to the second
voltage terminal.
11. The shift register of claim 1, wherein each of transistors in
the shift register is an N-type transistor.
12. The shift register of claim 11, wherein the second voltage
terminal is a low voltage terminal, the first voltage terminal and
the third voltage terminal are a high voltage terminal each.
13. The shift register of claim 12, wherein the interference
removing signal is one of a frame start signal and a control
signal.
14. A gate driving circuit, comprising N cascaded shift registers
as claimed in claim 1, N being a natural number, wherein the input
signal terminal of the shift register in a first stage is connected
to a frame start signal terminal, and the reset signal terminal of
the shift register in the first stage is connected to the output
terminal of the shift register in a next stage, the input signal
terminal of the shift register in a last stage is connected to the
output terminal of the shift register in a previous stage, the
reset signal terminal of the shift register in the last stage is
connected to the frame start signal terminal, as for the shift
register other than the shift register in the first stage and the
shift register in the last stage, the input signal terminal thereof
is connected to the output terminal of the shift register in a
previous stage, and the reset signal thereof is connected to the
output terminal of the shift register in a next stage, in the gate
driving circuit, a same interference removing signal is inputted to
the interference removing signal terminal of the shift register in
each stage.
15. The gate driving circuit of claim 14, wherein the interference
removing circuit comprises an interference removing transistor, a
gate and a first electrode of the interference removing transistor
are both connected to the interference removing signal terminal,
and a second electrode of the interference removing transistor is
connected to the pull-down node.
16. The gate driving circuit of claim 14, wherein the clock signal
terminal of the shift register in an n-th stage receives a first
clock signal, the clock signal terminal of the shift register in an
(n+1)-th stage receives a second clock signal, n being an integer
greater than zero and less than N.
17. The gate driving circuit of claim 15, wherein the interference
removing signal is an active control level signal after abnormity
occurs to an output signal of the shift register and before a next
frame signal arrives.
18. A display device, comprising the gate driving circuit as
claimed in claim 14.
19. A driving method for a shift register, the method comprising:
in a first period, the pull-up driving circuit outputs the voltage
signal of the first voltage terminal to the pull-up node and
charges the storage circuit under control of a signal inputted at
the input signal terminal, so that the pull-up circuit outputs the
clock signal of the clock signal terminal to the output terminal;
since the voltage signal of the first voltage terminal is outputted
to the pull-up node, the pull-down driving circuit pulls down the
pull-down node to the voltage signal of the second voltage
terminal, so that the pull-down circuit does not operate; in a
second period, the pull-up driving circuit does not operate under
control of the signal inputted at the input signal terminal, and
the pull-up node continues to maintain the voltage signal of the
first voltage terminal; the pull-up circuit remains in an operating
state, and the clock signal is outputted to the output terminal by
the pull-up circuit; the pull-up node is still at the voltage
signal of the first voltage terminal, and the pull-down node is
discharged by the pull-down driving circuit, so that the pull-down
circuit continues to remain in the non-operating state; in a third
period, the reset circuit operates to pull down the pull-up signal
at the pull-up node to the voltage signal at the second voltage
terminal under control of the reset signal inputted by the reset
signal terminal; since the pull-up node is at the voltage signal of
the second voltage terminal, the pull-up circuit does not operate;
in a fourth period, the pull-down driving circuit outputs the
voltage signal of the third voltage terminal to the pull-down node
under control of the voltage signal of the third voltage terminal;
when a level at the pull-down node is the voltage signal of the
third voltage terminal, the pull-down circuit operates to pull down
the pull-up node and the output terminal to the voltage signal of
the second voltage terminal, so as to de-noise the pull-up node and
the output terminal; and in a fifth period, when one frame ends and
before a next frame arrives, with the interference removing signal
at an active level, the interference removing circuit operates to
charge the pull-down node.
20. The driving method of claim 18, wherein the second voltage
terminal is a low voltage terminal; the first voltage terminal and
the third voltage terminal are a high voltage terminal each.
Description
CROSS-REFERENCES TO RELATED APPLICATIONS
[0001] This application claims priority to and the benefit of
Chinese Patent Application No. 201710132394.X filed on Mar. 7,
2017, which application is incorporated herein in its entirety.
TECHNICAL FIELD
[0002] The present disclosure relates to a shift register design
with low noise and high reliability for a bi-directional scan
driver of a liquid crystal display, and more particularly to a
shift register having a fault tolerance mechanism and a driving
method thereof, a gate driving circuit and a display.
BACKGROUND
[0003] Liquid crystal display panel makes displaying by adopting a
progressive scan matrix with M.times.N dots being arranged. TFT-LCD
(Thin Film Transistor-Liquid Crystal Display) driver mainly
includes a gate driver and a data driver, wherein the gate driver
converts an inputted clock signal through a shift register and
applies the converted signal to a gate line of the liquid crystal
display panel.
[0004] Shift register is commonly used in a gate driver of a liquid
crystal display panel, and each gate line is docked to a circuit
stage of the shift register. Gate input signals are outputted
through the gate driver, and pixels are scanned progressively. The
gate driver may be provided in a display panel in the encapsulated
form of COF (Chip On Film) or COG (Chip On Glass), or may be formed
in the display panel with an integrated circuit unit being
constituted by TFT. For the liquid crystal display panel, GOA (Gate
Driver on Array) design of the gate driver can reduce product cost,
also subtract a process and improve production capacity.
[0005] The present disclosure provides a new design of shift
register for gate driving of the liquid crystal display. The shift
register can quickly perform global reset when the output signal of
the circuit is abnormal.
SUMMARY
[0006] Parts of additional aspects and advantages of the present
disclosure will be set forth in the description which follows, and
parts of them will be obvious from the description, or may be
learned in practice of the present disclosure.
[0007] The present disclosure is directed to the design of a shift
register having a fault tolerance mechanism and a high reliability
and applicable to a scan driver of a liquid crystal display.
[0008] The present disclosure relates to a design method of a shift
register for gate scanning of a liquid crystal display, the shift
register can quickly perform global reset when the output signal of
the circuit is abnormal. The shift register comprises: a pull-up
circuit for outputting a driving signal to an output terminal
OUTPUT according to a high-level signal at an input signal terminal
INPUT and a clock signal terminal CLK or CLKB; a reset circuit for
outputting an OFF signal to the pull-up node PU through a reset
signal RESET, that is, an output terminal from a shift register in
a next stage; and a pull-down circuit for implementing de-noising
on the pull-up node PU and the output terminal OUTPUT through a
signal inputted from the pull-down node PD and the control circuit.
In a gate driving circuit, an input signal INPUT of the circuit in
each stage is an output signal OUTPUT in a previous stage; the
reset signal RESET of the circuit in each stage is an output signal
OUTPUT of a next stage. The most important is that an interference
removing circuit that uses the interference removing signal GLB to
control is added, thereby the global reset function is
achieved.
[0009] The present disclosure provides a shift register,
comprising: a pull-up driving circuit connected to an input signal
terminal, a first voltage terminal and a pull-up node, and
configured to output a voltage signal of the first voltage terminal
to the pull-up node when an input signal of the input signal
terminal is at an active input level; a pull-up circuit connected
to a clock signal terminal, the pull-up node and an output
terminal, and configured to output a clock signal of the clock
signal terminal to the output terminal when a pull-up signal of the
pull-up node is at an active pull-up level; a pull-down driving
circuit connected to a second voltage terminal, a third voltage
terminal, the pull-up node and a pull-down node, and configured to
control a potential at the pull-down node; a pull-down circuit
connected to the second voltage terminal, the pull-down node, the
pull-up node and the output terminal, and configured to pull down
the output terminal and the pull-up node to a voltage signal of the
second voltage terminal when a pull-down signal of the pull-down
node is at an active pull-down level; and an interference removing
circuit connected to an interference removing signal terminal and
the pull-down node, and configured to transmit an active
interference removing signal to the pull-down node to charge the
pull-down node when an interference removing signal outputted at
the interference removing signal terminal is at an active control
level.
[0010] The present disclosure further provides a gate driving
circuit comprising N cascaded shift registers as described above, N
being a natural number, wherein the input signal terminal of the
shift register in a first stage is connected to a frame start
signal terminal, and the reset signal terminal of the shift
register in the first stage is connected to the output terminal of
the shift register in a next stage, the input signal terminal of
the shift register in a last stage is connected to the output
terminal of the shift register in a previous stage, the reset
signal terminal of the shift register in the last stage is
connected to the frame start signal terminal, as for the shift
register other than the shift register in the first stage and the
shift register in the last stage, the input signal terminal thereof
is connected to the output terminal of the shift register in a
previous stage, and the reset signal thereof is connected to the
output terminal of the shift register in a next stage, in the gate
driving circuit, the interference removing signal is connected to
the shift register in each stage.
[0011] The present disclosure further provides a display device
comprising the gate driving circuit as described above.
[0012] The present disclosure further provides a driving method for
a shift register, the method comprising: in a first period, the
pull-up driving circuit outputs the voltage signal of the first
voltage terminal to the pull-up node and charges a storage circuit
under control of a signal inputted at the input signal terminal, so
that the pull-up circuit outputs the clock signal of the clock
signal terminal to the output terminal; since the voltage signal of
the first voltage terminal is outputted to the pull-up node, the
pull-down driving circuit pulls down the pull-down node to the
voltage signal of the second voltage terminal, so that the
pull-down circuit does not operate; in a second period, the pull-up
driving circuit does not operate under control of the signal
inputted at the input signal terminal, and the pull-up node
continues to maintain the voltage signal of the first voltage
terminal; the pull-up circuit remains in an operating state, and
the clock signal is outputted to the output terminal by the pull-up
circuit; the pull-up node is still at the voltage signal of the
first voltage terminal, and the pull-down node is discharged by the
pull-down driving circuit, so that the pull-down circuit continues
to remain in the non-operating state; in a third period, the reset
circuit operates to pull down the pull-up signal at the pull-up
node to the voltage signal at the second voltage terminal under
control of the reset signal inputted by the reset signal terminal;
since the pull-up node is at the voltage signal of the second
voltage terminal, the pull-up circuit does not operate; in a fourth
period, the pull-down driving circuit outputs the voltage signal of
the third voltage terminal to the pull-down node under control of
the voltage signal of the third voltage terminal; when a voltage at
the pull-down node is the voltage signal of the third voltage
terminal, the pull-down circuit operates to pull down the pull-up
node and the output terminal to the voltage signal of the second
voltage terminal, so as to de-noise the pull-up node and the output
terminal; and in a fifth period, when one frame ends and before a
next frame arrives, with the interference removing signal at an
active level, the interference removing circuit operates to charge
the pull-down node.
BRIEF DESCRIPTION OF THE DRAWINGS
[0013] The above and other objects, features and advantages of the
present disclosure will become more apparent from the following
detailed description of the preferred embodiments of the present
disclosure as provided in conjunction with the accompanying
drawings in which like reference numerals indicate elements of like
structures:
[0014] FIG. 1 shows a block diagram of an exemplary circuit
configuration of a shift register according to an embodiment of the
present disclosure;
[0015] FIG. 2 shows an exemplary circuit configuration diagram of a
shift register according to an embodiment of the present
disclosure;
[0016] FIG. 3 shows a first schematic diagram of a gate driving
circuit formed by cascading a plurality of shift registers
according to an embodiment of the present disclosure;
[0017] FIG. 4 shows a second schematic diagram of a gate driving
circuit formed by cascading a plurality of shift registers
according to an embodiment of the present disclosure;
[0018] FIG. 5 shows a timing diagram of scanning of a shift
register according to an embodiment of the present disclosure;
and
[0019] FIG. 6 shows a flow chart of a driving method for a shift
register according to an embodiment of the present disclosure.
DETAILED DESCRIPTION OF THE EMBODIMENTS
[0020] Hereinafter, the present disclosure will be described fully
with reference to the accompanying drawings that illustrate the
embodiments of the present disclosure. However, the present
disclosure may be implemented in many different forms and should
not be construed as limited to the embodiments described herein.
Contrarily, these embodiments are provided to make the present
disclosure be thorough and complete, and to fully convey the scope
of the present disclosure to those skilled in the art. In the
drawings, the components are enlarged for clarity.
[0021] Each of the transistors adopted in all of the embodiments of
the present disclosure may be a thin film transistor or an FET
(Field Effect Transistor), or other devices of the same properties.
In the embodiments of the present disclosure, connection of a
source and a drain of each transistor may be interchanged, the
source and the drain of each transistor in the embodiments of the
present disclosure have no difference practically. Here, in order
to distinguish the two electrodes other than the gate, one
electrode is referred to as a drain, and the other electrode is
referred to as a source.
[0022] For the purpose of facilitating further understanding of the
present disclosure, the present disclosure will now be described in
detail with reference to the accompanying drawings.
[0023] FIG. 1 shows a block diagram of an exemplary circuit
configuration of a shift register according to an embodiment of the
present disclosure.
[0024] The shift register shown in FIG. 1 comprises a pull-up
driving circuit 101, a pull-up circuit 102, a pull-down driving
circuit 103, a pull-down circuit 104, and an interference removing
circuit 105.
[0025] The pull-up driving circuit 101 is connected to an input
signal terminal INPUT, a first voltage terminal VDD and a pull-up
node PU, and configured to output a voltage signal of the first
voltage terminal VDD to the pull-up node PU when an input signal of
the input signal terminal INPUT is at an active input level.
[0026] The pull-up circuit 102 is connected to a clock signal
terminal CLK, the pull-up node PU and an output terminal OUTPUT,
and configured to output a clock signal of the clock signal
terminal CLK to the output terminal OUTPUT when a pull-up signal of
the pull-up node PU is at an active pull-up level.
[0027] The pull-down driving circuit 103 is connected to a second
voltage terminal VGL, a third voltage terminal GCH, the pull-up
node PU and a pull-down node PD, and configured to control a
potential at the pull-down node PD. For example, when the pull-up
signal at the pull-up node PU is at an active pull-up level, the
pull-down driving circuit 103 generates a pull-down signal at an
inactive pull-down level at the pull-down node PD; when the pull-up
signal at the pull-up node PU is at an inactive pull-up level, the
pull-down driving circuit 103 supplies a voltage signal at the
third voltage terminal GCH to the pull-down node PD in response to
the voltage signal at the third voltage terminal GCH.
[0028] The pull-down circuit 104 is connected to the second voltage
terminal VGL, the pull-down node PD, the pull-up node PU and the
output terminal OUTPUT, and configured to pull down the output
terminal OUTPUT and the pull-up node PU to a voltage signal of the
second voltage terminal VGL when a pull-down signal of the
pull-down node PD is at an active pull-down level.
[0029] The interference removing circuit 105 is connected to an
interference removing signal terminal GLB and the pull-down node
PD, and configured to transmit an active interference removing
signal GLB to the pull-down node PD to charge the pull-down node PD
when the interference removing signal GLB at the interference
removing signal terminal is at an active control level.
[0030] The interference removing signal GLB is provided with an
active control level after abnormity occurs to an output signal of
the shift register and before a next frame signal arrives.
[0031] The interference removing signal may be a frame start signal
STV or a control signal CTR.
[0032] The first voltage terminal VDD and the third voltage
terminal GCH are a high voltage terminal each, the second voltage
terminal VGL is a low voltage terminal.
[0033] In the embodiment of the present disclosure, the shift
register is additionally provided with the interference removing
circuit 105 controlled through the interference removing signal
GLB, a level of the pull-down node PD is controlled by the
interference removing circuit 105. When GLB is at a high level, the
pull-down node PD also is at a high level, so that the pull-down
circuit 104 will begin to operate and discharge the pull-up node PU
and the output terminal OUTPUT.
[0034] The shift register according to an embodiment of the present
disclosure may further comprise a storage circuit C1. A first
terminal of the storage circuit C1 is connected to the pull-up node
PU and a second terminal of the storage circuit C1 is connected to
the output terminal OUTPUT, and the storage circuit C1 is
configured to be charged when the voltage signal of the first
voltage terminal is outputted to the pull-up node PU.
[0035] The shift register according to an embodiment of the present
disclosure may further comprise a reset circuit 106. The reset
circuit 106 is connected to a reset signal terminal RESET, the
second voltage terminal VGL and the pull-up node PU, and configured
to pull down the pull-up signal of the pull-up node PU to the
voltage signal of the second voltage terminal VGL when a reset
signal at the reset signal terminal RESET is at an active control
level.
[0036] FIG. 2 shows an exemplary circuit configuration diagram of a
shift register according to an embodiment of the present
disclosure.
[0037] FIG. 2 is a circuit diagram of a specific implementation of
FIG. 1, including TFT transistors M1 to M10 and a capacitor C1.
Next, description is provided with each of the transistors in FIG.
2 being an N-type transistor which is turned on when a high level
is inputted at the gate thereof as an example.
[0038] As shown in FIG. 2, in an embodiment, for example, the
pull-up driving circuit 101 comprises a pull-up driving transistor
M1. A gate of the pull-up driving transistor M1 is connected to the
input signal terminal INPUT, a first electrode of the pull-up
driving transistor M1 is connected to the first voltage terminal
VDD, and a second electrode of the pull-up driving transistor M1 is
connected to the pull-up node PU. When the input signal at the
input signal terminal INPUT is at a high level, the pull-up driving
transistor M1 is turned on and the voltage signal at the first
voltage terminal VDD is outputted to the pull-up node PU.
[0039] In an embodiment, the pull-up circuit 102 comprises an
output transistor M3. A gate of the output transistor M3 is
connected to the pull-up node PU, a first electrode of the output
transistor M3 is connected to the clock signal terminal CLK, and a
second electrode of the output transistor M3 is connected to the
output terminal OUTPUT. When the pull-up signal at the pull-up node
PU is at a high level, the output transistor M3 is turned on, and
the clock signal at the clock signal terminal CLK is outputted to
the output terminal OUTPUT.
[0040] In an embodiment, for example, the pull-down driving circuit
103 comprises a first pull-down driving transistor M8, a second
pull-down driving transistor M9, a third pull-down driving
transistor M4 and a fourth pull-down driving transistor M5. A gate
of the first pull-down driving transistor M8 is connected to a
second electrode of the third pull-down driving transistor M4, a
first electrode of the first pull-down driving transistor M8 is
connected to the third voltage terminal GCH, and a second electrode
of the first pull-down driving transistor M8 is connected to the
pull-down node PD; a gate of the second pull-down driving
transistor M9 is connected to the pull-up node PU, a first
electrode of the second pull-down driving transistor M9 is
connected to the pull-down node PD, and a second electrode of the
second pull-down driving transistor M9 is connected to the second
voltage terminal VGL; a gate and a first electrode of the third
pull-down driving transistor M4 are connected to the third voltage
terminal GCH; a gate of the fourth pull-down driving transistor M5
is connected to the pull-up node PU, a first electrode of the
fourth pull-down driving transistor M5 is connected to the second
electrode of the third pull-down driving transistor M4, and a
second electrode of the fourth pull-down driving transistor M5 is
connected to the second voltage terminal VGL.
[0041] In an embodiment, for example, the pull-down circuit 104
comprises a node pull-down transistor M6 and an output pull-down
transistor M7. A gate of the node pull-down transistor M6 and a
gate of the output pull-down transistor M7 are connected to the
pull-down node PD, a first electrode of the node pull-down
transistor M6 is connected to the pull-up node PU, a first
electrode of the output pull-down transistor M7 is connected to the
output terminal OUTPUT, a second electrode of the node pull-down
transistor M6 and a second electrode of the output pull-down
transistor M7 are connected to the second voltage terminal VGL.
When the pull-down signal at the pull-down node PD is at a high
level, the node pull-down transistor M6 and the output pull-down
transistor M7 are turned on, so as to pull down the pull-up node PU
and the output terminal OUTPUT to the voltage signal at the second
voltage terminal VGL, respectively.
[0042] In an embodiment, for example, the interference removing
circuit 105 comprises an interference removing transistor M10. A
gate and a first electrode of the interference removing transistor
M10 are both connected to the interference removing signal terminal
GLB, and a second electrode of the interference removing transistor
M10 is connected to the pull-down node PD.
[0043] In an embodiment, for example, the storage circuit comprises
a capacitor C1, a first terminal of the capacitor C1 is connected
to the pull-up node PU, and a second terminal of the capacitor C1
is connected to the output terminal OUTPUT. When the pull-up
driving transistor M1 is turned on, the capacitor C1 is charged by
the high-level signal of the first voltage terminal VDD.
[0044] In an embodiment, for example, the reset circuit 106
comprises a reset transistor M2. A gate of the reset transistor M2
is connected to the reset signal terminal RESET, a first electrode
of the reset transistor M2 is connected to the pull-up node PU, and
a second electrode of the reset transistor M2 is connected to the
second voltage terminal VGL. The reset transistor M2 is turned on
when the reset signal at the reset signal terminal RESET is at a
high level, so that the pull-up signal at the pull-up node PU is
pulled down to the voltage signal of the second voltage terminal
VGL.
[0045] FIG. 3 shows a first schematic diagram of a gate driving
circuit formed by cascading a plurality of shift registers
according to an embodiment of the present disclosure.
[0046] The gate driving circuit shown in FIG. 3 comprises a
plurality of cascaded shift registers. The shift register in each
stage may be constructed by using the structure described
below.
[0047] The input signal terminal of the shift register in a first
stage is connected to a frame start signal terminal, a start signal
at the frame start signal terminal is a pulse signal for activating
the shift register, optionally, such as the frame start signal STV,
and the reset signal terminal of the shift register in the first
stage is connected to the output terminal of the shift register in
a next stage.
[0048] The input signal terminal of the shift register in a last
stage is connected to the output terminal of the shift register in
a previous stage, and the reset signal terminal of the shift
register in the last stage is connected to the frame start signal
terminal STV.
[0049] As for the shift register other than the shift register in
the first stage and the shift register in the last stage, the input
signal terminal thereof is connected to the output terminal of the
shift register in a previous stage, and the reset signal thereof is
connected to the output terminal of the shift register in a next
stage. All cascaded shift registers can adopt the shift register
shown in FIGS. 1 and 2.
[0050] As shown in FIG. 3, in the gate driving circuit of the
present application, the frame start signal STV is connected, as
the interference removing signal GLB, to the shift register in each
stage, so that after abnormality occurs to the output signal of the
shift register, an active control level is supplied before a next
frame signal arrives, so as to globally reset all shift
registers.
[0051] FIG. 4 shows a second schematic diagram of a gate driving
circuit formed by cascading a plurality of shift registers
according to an embodiment of the present disclosure.
[0052] The gate driving circuit shown in FIG. 4 comprises a
plurality of cascaded shift registers. The shift register in each
stage may be constructed by using the structure described
below.
[0053] The input signal terminal of the shift register in a first
stage is connected to a frame start signal terminal, a start signal
at the frame start signal terminal is a pulse signal for activating
the shift register, optionally, such as the frame start signal STV,
and the reset signal terminal of the shift register in the first
stage is connected to the output terminal of the shift register in
a next stage.
[0054] The input signal terminal of the shift register in a last
stage is connected to the output terminal of the shift register in
a previous stage, and the reset signal terminal of the shift
register in the last stage is connected to the frame start signal
terminal STV.
[0055] As for the shift register other than the shift register in
the first stage and the shift register in the last stage, the input
signal terminal thereof is connected to the output terminal of the
shift register in a previous stage, and the reset signal thereof is
connected to the output terminal of the shift register in a next
stage. All cascaded shift registers can adopt the shift register
shown in FIGS. 1 and 2.
[0056] As shown in FIG. 4, in the gate driving circuit of the
present application, one control signal CTR is added as the
interference removing signal GLB to be connected to the shift
register in each stage, so that after abnormality occurs to the
output signal of the shift register, an active control level is
supplied before a next frame signal arrives, so as to globally
reset all shift registers.
[0057] The two schemes in FIGS. 3 and 4 both are performing global
reset on all the registers after the output signal becomes
disordered and before a next frame signal arrives.
[0058] FIG. 5 shows a timing diagram of scanning of a shift
register according to an embodiment of the present disclosure.
[0059] FIG. 5 is a timing diagram of the two schemes shown in FIGS.
3 and 4 of the present disclosure. When the output signal is
normal, the shift register operates normally, and the interference
removing circuit 105 operates when the interference removing signal
GLB (i.e., STV or CTR) is at a high level, it does not affect the
normal operating state.
[0060] In a first period, the input signal terminal INPUT has a
high-level signal, so that the pull-up driving transistor M1 is
turned on; the high-level signal of the first voltage terminal VDD
charges the capacitor C1, at this moment, a level at the pull-up
node PU is pulled up, so that the output transistor M3 is turned
on, in this case, the clock signal at the clock signal terminal CLK
is at a low level, the output terminal OUTPUT outputs a low level.
Further, since the pull-up node PU is at a high level, the second
pull-down driving transistor M9 and the fourth pull-down driving
transistor M5 are turned on, so that the pull-down node PD is at a
low level, consequently, the node pull-down transistor M6 and the
output pull-down transistor M7 are turned off. In addition, in this
period, the reset signal at the reset signal terminal RESET is at a
low level, and the reset transistor M2 is turned off. Thereby,
stability of signal output is ensured.
[0061] In a second period, when the input signal terminal INPUT is
at a low level, the pull-up driving transistor M1 is turned off,
the pull-up node PU continues to remain a high level, and the
output transistor M3 remains a turned-on state. The reset signal
terminal RESET is at a low level and the reset transistor M2
remains turned-off. At this moment, the clock signal at the clock
signal terminal CLK is at a high level, in this case, the high
level of the clock signal is outputted to the output terminal, and
the voltage at the pull-up node PU is raised because of
bootstrapping effect of the capacitor C1. At this moment, the
pull-up node PU is still at a high level, and the second pull-down
driving transistor M9 and the fourth pull-down driving transistor
M5 remain turned-on to discharge the pull-down node PD, so that the
node pull-down transistor M6 and the output pull-down transistor M7
continue to remain turned-off. Thereby, stability of signal output
is ensured.
[0062] In a third period, the input signal terminal INPUT is at a
low level, the input transistor M1 remains turned-off. When the
reset signal at the reset terminal RESET is a high-level signal
(the reset signal is the output of the shift register in a next
stage), the high-level signal at the reset signal terminal causes
the reset transistor M2 to be turned on, the pull-up signal at the
pull-up node PU is pulled down to the voltage signal at the second
voltage terminal VGL. Since the pull-up node PU is at a low level,
the output transistor M3 is turned off.
[0063] In a fourth period, the clock signal terminal CLK is at a
high level, the clock signal at CLKB is at a low level, and the
third voltage terminal GCH has a high-level voltage signal. At this
moment, the third pull-down driving transistor M4 is turned on,
since the pull-up node PU is discharged by the reset transistor M2
in the previous period, in this case, the second pull-down driving
transistor M9 and the fourth pull-down driving transistor M5 are in
a turned-off state. In this case, the first pull-down driving
transistor M8 is turned on to charge the pull-down node PD; at this
moment, a level at the pull-down node PD is pulled up, so as to
turn on the node pull-down transistor M6 and the output pull-down
transistor M7, such that the pull-up node PU and output terminal
OUTPUT are pull down to the voltage signal at the second voltage
terminal VGL and the pull-up node PU and the output terminal OUTPUT
are de-noised. As a result, a coupling noise voltage generated by
the clock signal terminal CLK can be eliminated, thereby low
voltage output is ensured, and stability of signal output is
ensured. As long as the pull-up node PU is at a high level (the
pull-up node PU in a current stage is charged), the pull-down node
PD is at a low level; as long as the pull-up node PU is at a low
level, the pull-down node PD is always at a high level, the node
pull-down transistor M6 and the output pull-down transistor M7 are
always turned on, so as to de-noise the pull-up node PU and the
output terminal OUTPUT.
[0064] In a fifth period, when one frame ends and before a next
frame arrives, the interference removing signal GLB (i.e., STV or
CTR) is an active control signal, thereby the interference removing
transistor M10 is turned on, and the interference removing
transistor M10 charges the pull-down node PD, the pull-down node PD
is at a high level, which will de-noise the pull-up node PU, thus
avoiding bad effects due to charge accumulation at the pull-up node
PU.
[0065] When one frame ends and before a next frame arrives refers
to: after the shift register scans from the first row to the last
row and before the shift register starts the repeated scan process
again.
[0066] Here, when the clock signal terminal connected to the shift
register in a G(n)-th stage is CLK, the clock signal terminal
connected to the shift register in a G(n+1)-th stage is CLKB.
[0067] When signal of one frame is abnormal, the pull-up node PU
cannot discharge, but before the arrival of the next frame of
signal, the interference removing signal GLB (i.e. STV or CTR) is
an active control signal first, thus the interference removing
transistor M10 is turned on, so that the pull-down node PD is at a
high level, so as to discharge the pull-up node PU before the clock
signal CLK arrives, consequently, there is no erroneous output,
product quality and reliability are higher with the fault-tolerant
mechanism being added.
[0068] FIG. 5 is merely an implementation example of the present
disclosure, and the present disclosure is not limited thereto.
[0069] FIG. 6 shows a flow chart of a driving method for a shift
register according to an embodiment of the present disclosure.
[0070] In a first period, the pull-up driving circuit outputs the
voltage signal of the first voltage terminal to the pull-up node
and charges the storage circuit under control of a signal inputted
at the input signal terminal, so that the pull-up circuit outputs
the clock signal of the clock signal terminal to the output
terminal; since the voltage signal of the first voltage terminal is
outputted to the pull-up node, the pull-down driving circuit pulls
down the pull-down node to the voltage signal of the second voltage
terminal, so that the pull-down circuit does not operate
(S601).
[0071] In a second period, the pull-up driving circuit does not
operate under control of the signal inputted at the input signal
terminal, and the pull-up node continues to maintain the voltage
signal of the first voltage terminal; the pull-up circuit remains
in an operating state, and the clock signal is outputted to the
output terminal by the pull-up circuit; the pull-up node is still
at the voltage signal of the first voltage terminal, and the
pull-down node is discharged by the pull-down driving circuit, so
that the pull-down circuit continues to remain in the non-operating
state (S602).
[0072] In a third period, the reset circuit operates to pull down
the pull-up signal at the pull-up node to the voltage signal at the
second voltage terminal under control of the reset signal inputted
by the reset signal terminal; since the pull-up node is at the
voltage signal of the second voltage terminal, the pull-up circuit
does not operate (S603).
[0073] In a fourth period, the pull-down driving circuit outputs
the voltage signal of the third voltage terminal to the pull-down
node under control of the voltage signal of the third voltage
terminal; when the pull-down node is at the voltage signal of the
third voltage terminal, the pull-down circuit operates to pull down
the pull-up node and the output terminal to the voltage signal of
the second voltage terminal, so as to de-noise the pull-up node and
the output terminal (S604).
[0074] In a fifth period, when one frame ends and before a next
frame arrives, with the interference removing signal at an active
level, the interference removing circuit operates to charge the
pull-down node (S605).
[0075] The structure of the new shift register with the fault
tolerance mechanism provided in the present disclosure not only
considers the lifespan of the shift register and the related
problems of reliability, but also has some tolerance mechanism for
signal disorder.
[0076] Unless otherwise defined, all terms (including technical and
scientific terms) used herein have the same meaning as commonly
understood by one of ordinary skill in the art to which example
embodiments belong. It will be further understood that terms, e.g.,
those defined in commonly used dictionaries, should be interpreted
as having a meaning that is consistent with their meaning in the
context of the relevant art and will not be interpreted in an
idealized or overly formal sense unless expressly so defined
herein.
[0077] The foregoing is description of the present disclosure and
should not be construed as limiting the present disclosure.
Although several exemplary embodiments of the present disclosure
have been described, those skilled in the art will readily
appreciate that many modifications may be made to the exemplary
embodiments without departing from the novel teachings and
advantages of the present disclosure. Accordingly, all such
modifications are intended to be included within the scope of the
present disclosure as defined by the claims. It is to be understood
that the foregoing is description of the present disclosure and
should not be construed as limited to the particular embodiments
disclosed herein, and modifications to the disclosed embodiments
and other embodiments are intended to be included within the scope
of the appended claims. The present disclosure is defined by the
claims and their equivalents.
* * * * *